The present invention relates to an image forming device such as a digital copier, a digital composite device, or a facsimile device which has a function for reading an image. More specifically, the present invention relates to zoom control performed by the image forming device to read an image from a document to form a scale factor changed image.
A conventional image forming device comprises image reading means for reading an image, image storage means for storing the image data read by the image reading means, image forming means for reading the image data stored in the image storage means and forming an image on a sheet on the basis of the image data, and setting means for setting an operator specified scale factor for the image on the document, the operator specified scale factor being a final image formation scale factor specified by the operator. The image forming device has zoom control that forms a scale factor changed image. Further, the image reading means for reading an image is composed of a first carriage on which a light source irradiating the document with light and a mirror reflecting reflected light from the document to a light receiving side are mounted, a second carriage on which a mirror reflecting the reflected light from the document to the light receiving side is mounted, a lens that forms an image, and photoelectric converting means (CCD) for converting the image into an electric signal. The photoelectric converting means (CCD) receives the reflected light for the image as line-like reflected light traveling in a main scanning direction. The photoelectric converting means then converts the reflected light into an electric signal. The photoelectric converting means may be called a CCD line sensor.
In this case, the first and second carriages are called a scanner. The first and second carriages are driven with wires. The second carriage moves at a speed half that of the first carriage. Further, the speed at which the first carriage of the scanner moves is defined as the speed at which the document is read (the moving speed of the first carriage will hereinafter be referred to as a scanner moving speed or reading speed).
A proposal has been made of the following technique. A conventional digital copier or digital composite device uses the image reading means to move a lens that forms an image in association with a reading scale factor of 100%, thus reading the image from the document. The 100% image data (hereinafter referred to as scale factor-equalized image data) is stored in an internal memory. The scale factor of the scale factor-equalized image data is changed in accordance with the operator specified scale factor. Then, a scale factor-changed image can be re-formed on the sheet (see, for example, Document 1 or Document 2).
However, this technique performs control that stores the scale factor-equalized image data in the internal memory and changes the scale factor of the image data in accordance with the operator specified scale factor. Accordingly, a problem with this technique is that the relevant burden on the memory or image scale factor changing process becomes heavier, which reduces the number of pages for image data which can be read.
On the other hand, instead of the above control, another type of image forming device performs control which, upon reading, reads the image while changing the scanner moving speed in accordance with the operator specified scale factor and which then stores the scale factor-changed image data in the internal memory, the control subsequently forming the corresponding scale factor-changed image on the sheet. This control differs from the above and, upon reading, reads the image having its scale factor changed. This control varies the scanner moving speed in increments of 1% in accordance with the operator specified scale factor, which ranges widely from, for example, 25 to 400%. It is thus necessary to employ a motor that does not vibrate vigorously over a wide range of scanner moving speeds, as well as its driving circuit. This disadvantageously increases costs. Thus, in recent years, a technique called hybrid zoom control has been proposed (Document 3).
In hybrid zoom control, the document is read using a predetermined reading scale factor and at a reading speed corresponding to the reading scale factor, and stores and holds the read data in the storage section. Image processing is then executed, that is, enlargement, contraction, or scale factor equalizing to enable a scale factor-changed image to be output. The predetermined scale factor may be the same as or different from the operator specified scale factor. If the operator specified scale factor is the same as the predetermined reading scale factor, the image processing is an image scale factor equalizing process. If the operator specified scale factor is larger than the predetermined reading scale factor, the image processing is an image enlarging process. If the operator specified scale factor is smaller than the predetermined reading scale factor, the image processing is an image contracting process.
The employment of the hybrid zoom control eliminates the need to vary the scanner moving speed in increments of 1% in accordance with the operator specified scale factor, which ranges widely from, for example, 25 to 400%. This in turn obviates the need for an expensive scanner motor and its driving circuit, thus reducing the cost.
[Patent Document 1] Jpn. Pat. Appln. KOKAI Publication No. 2003-87522 (Document 1)
[Patent Document 2] Jpn. Pat. Appln. KOKAI Publication No. 2003-87522 (Document 2)
[Patent Document 3] Jpn. Pat. Appln. KOKAI Publication No. 2001-77980 (Document 3)